Engine Fuel & Emission Control System
NEF390 ECM (ECCS-D control module)
lDo not disassemble ECM.lIf a battery terminal is disconnected, the memory
will return to the ECM value.
The ECM will now start to self-control at its initial
value. Engine operation can vary slightly when
the terminal is disconnected. However, this is not
an indication of a problem. Do not replace parts
because of a slight variation.
lWhen ECM is removed for inspection, make sure
to ground the ECM mainframe.WIRELESS EQUIPMENT
lWhen installing C.B. ham radio or a mobile
phone, be sure to observe the following as it
may adversely affect electronic control sys-
tems depending on its installation location.
1) Keep the antenna as far as possible away
from the ECM.
2) Keep the antenna feeder line more than
20 cm (7.9 in) away from the harness of elec-
tronic controls.
Do not let them run parallel for a long dis-
tance.
3) Adjust the antenna and feeder line so that the
standing-wave ratio can be kept small.
4) Be sure to ground the radio to vehicle body.
ECM HARNESS HANDLING
lConnect ECM harness connectors securely.
A poor connection can cause an extremely
high (surge) voltage to develop in coil and
condenser, thus resulting in damage to ICs.
lKeep ECM harness at least 10 cm (3.9 in)
away from adjacent harnesses, to prevent an
ECM system malfunction due to receiving
external noise, degraded operation of ICs,
etc.
lKeep ECM parts and harnesses dry.lBefore removing parts, turn off ignition
switch and then disconnect battery ground
cable. WHEN STARTING
lDo not depress accelerator pedal when
starting.
lImmediately after starting, do not rev up
engine unnecessarily.
lDo not rev up engine just prior to shut-
down. ECM PARTS HANDLING
lHandle mass air flow sensor carefully to avoid
damage.
lDo not disassemble mass air flow sensor.lDo not clean mass air flow sensor with any type
of detergent.
lDo not disassemble No. 1 injection nozzle (built-
in needle lift sensor).
lEven a slight leak in the air intake system can
cause serious problems.
lDo not shock or jar the camshaft position sensor
(TDC). ELECTRONIC FUEL INJECTOR PUMP
lDo not disconnect pump harness connectors
with engine running.
lDo not disassemble or adjust electronic fuel
injection pump, except for the following
parts.
Camshaft position sensor (pump)
Injection timing control valve
Fuel cut solenoid valve BATTERY
lAlways use a 12 volt battery as power
source.
lDo not attempt to disconnect battery cables
while engine is running.
ECM mainframe
PRECAUTIONS AND PREPARATIONCD20T
EC-5
Trouble Diagnoses
Symptom Possible cause Repair order
Radio inoperative (no digital
display and no sound from
speakers).1. 10A Fuse
2. Poor radio case ground
3. Radio1. Check 10A fuse [No.
3 , located in fuse block
(J/B)]. Turn ignition switch ON and verify battery
positive voltage is present at terminal
3of radio
2. Check radio case ground.
3. Remove radio for repair.
Radio controls are
operational, but no sound is
heard from any speaker.1. Radio output
2. Radio1. Check radio output voltages.
2. Remove radio for repair.
Radio presets are lost
when ignition switch is
turned OFF.1. 15A fuse
2. Radio1. Check 15A fuse [No.
35 , located in fuse and fus-
ible box and verify battery positive voltage is
present at terminal
9of radio.
2. Remove radio for repair.
Individual speaker is noisy
or inoperative.1. Speaker
2. Radio output
3. Speaker circuit
4. Radio1. Check speaker
2. Check radio output voltages.
3. Check wires for open or short between radio and
speaker.
4. Remove radio for repair.
Radio stations are weak or
noisy.1. Antenna
2. Poor radio ground
3. Radio1. Check antenna.
2. Check radio ground.
3. Remove radio for repair.
Radio generates noise in
AM and FM modes with
engine running.1. Poor radio ground
2. Loose or missing ground bonding
straps
3. Ignition condenser or rear window
defogger noise suppressor con-
denser
4. Alternator
5. Ignition coil or secondary wiring
6. Radio1. Check radio ground.
2. Check ground bonding straps.
3. Replace ignition condenser or rear window defogger
noise suppressor condenser.
4. Check alternator
5. Check ignition coil and secondary wiring.
6. Remove radio for repair.
Radio generates noise in
AM and FM modes with
accessories on (switch
pops and motor noise).1. Poor radio ground
2. Antenna
3. Accessory ground
4. Faulty accessory1. Check radio ground.
2. Check antenna.
3. Check accessory ground.
4. Replace accessory.
AUDIO
EL-226
